Abstract This article builds on computational tools to investigate the syntactic relationship between the highly related European national varieties of Dutch, viz. Belgian Dutch (BD) and Netherlandic Dutch (ND). It reports on a series of memory-based learning analyses of the post-verbal distribution of er “there” in adjunct-initial existential constructions like Op het dak staat (er) een schoorsteen “On the roof (there) is a chimney,’, which has been claimed to be among the most notoriously difficult variables in Dutch. On the basis of balanced datasets extracted from Flemish and Dutch newspaper corpora, it is shown that er ’s distribution in both national varieties can be learned to a considerable extent from bare lexical input which is not assigned to higher-level categories. However, whereas this yields good results for ND, BD scores are consistently lower, suggesting that BD cannot do with lexical features alone to attain accuracy scores comparable to ND. This ties in with earlier findings that the more advanced standardization of ND materializes in a higher lexical collocability, whereas Flemish speakers need additional higher-level linguistic information to insert er .